This proposal seeks funds to purchase a blood flow measuring, Doppler-ultrasound instrument for use by four user groups. Recent advent of combined Doppler flowmetry with real time imaging has added new dimension to our diagnostic ability with ultrasonagraphy. Using such an advanced and sophisticated device currently available in the market, (Diasonics, DRF-400), the user groups will image central and peripheral vessels of their study population, measure blood vessel diameter and cross sectional area, calculate average flow volume and velocity profiles, and thus derive additional insights into the pathophysiological processes. USER GROUP I: Life threatening and disabling illnesses in sickle hemoglobinophathies are related to episodic vasoocclusive phenomenae and, therefore, in a group of such children central and peripheral blood flow studies will be carried out longitudinally. Knowledge of flow characteristics before and during illness is expected to provide valuable information about the pathogenesis of episodic disorders in these conditions. USER GROUP II: Pregnant women with phenylketonuria (PKU), hypertension, diabetes and sickle hemoglobinopathies have high fetal mortality and morbidity. Monitoring utero-placental and fetal blood flow, and fetal tissue imaging, therefore, would provide crucial measures of fetal well being. Mothers with the above conditions will be studied by this group; the results would help develop specific protocols for timely therapy and intervention. USER GROUP III: Premature infants with very high risk for intracranial hemorrhage, asphyxial brain damage, retrolental fibroplasia and other devastating conditions will be studied by this group. Despite the suggestion from animal studies that alterations in blood flow characteristics play central role in the etiology of these conditions, little is known in human infants. Thus, this project helps to understand pathophysiology of severe morbidity factors in newborns. USER GROUP IV: An in-vitro project involving study of echogenic properties of fetal blood (obtained from the placenta after delivery), will be carried out by this group which is expected to lay foundations in understanding fetal blood shear rates, factors influencing Doppler echo at different gestations, and maternal-fetal health status.